April 14, 2017 — For the first time, scientists have recorded a spring fish migration by conducting DNA tests on water samples.

The work was a collaboration of Rockefeller University and the Urban Coast Institute at Monmouth University.

According to the study’s report, environmental DNA called eDNA, collected from one-liter samples drawn weekly from New York’s East and Hudson rivers over six months last year, revealed the presence or absence of several key fish species passing through the water on each test day.

The bits of DNA recovered found the presence of menhaden, herring species, black sea bass, striped bass, tautog (blackfish), mummichog, bay anchovy, bluefish, oyster toadfish, Atlantic silverside, and conger eel. In total it found the presence of 42 species.

Using eDNA is a way to monitor fish migrations that involves a fraction of the effort and cost of trawling, all without harming the fish, the study said.

It also said it can be used to estimate the abundance and distribution of diverse fish species and other forms of marine life in the dark waters of rivers, lakes, and seas.

February 13, 2016 — The waterways surrounding New York City are a soup of plastic, ranging from discarded takeout containers down to tiny beads that end up in the food supply, according to a new report by an environmental group.

The study, by the group NY/NJ Baykeeper, estimated there are at least 165 million plastic particles floating in New York Harbor and nearby waters at any given time.

The report was based on samples collected by trawlers that plied the city’s East River, the mouth of the Hudson River and New Jersey’s Passaic River and Raritan Bay between March and August 2015.

The average concentration of plastics was 256,322 particles per square kilometer, according to the report.

To maybe nobody’s surprise, the highest concentration, 556,484 particles per square kilometer, was found in New York City’s East River, which separates Manhattan from Brooklyn and Queens and is known for its floating filth.

“It just goes to show you big problems need big solutions,” said Sandra Meola, a spokeswoman for Baykeeper.

The New York-New Jersey study was modeled on a pioneering study of the Great Lakes conducted by Sherri Mason, a chemistry professor at the State University of New York in Fredonia.

That study found plastics pollution in all five lakes, with the highest concentration in Lakes Erie and Ontario, which are ringed by urban centers and industry.